1. Field of the Invention
The present invention relates to a sheet feeding apparatus and an image forming apparatus which forms an image on a sheet fed by this sheet feeding apparatus.
2. Description of the Related Art
Conventionally, an image forming apparatus such as a copying machine or printer which forms an image on a sheet is generally equipped with cassettes which accommodate a great amount of sheets of regular sizes. Further, an image forming apparatus of some type is equipped with a so-called manual sheet feeding apparatus which feeds sheets such as sheets of an irregular size such as postcards, OHP or special paper placed by the user on the side of the apparatus body.
This manual sheet feeding apparatus is discussed in Japanese Patent Laid-Open No. 06-009064. With this sheet feeding apparatus, the user moves side regulating plates which are a pair of aligning members provided in a manual feed tray, to come close to and separate from each other to align the widths of sheets in a direction crossing a sheet feeding direction. Further, with the sheet feeding apparatus, a detecting portion detects the sheet width size based on the movement amount of the side regulating plates. Furthermore, the sheet feeding apparatus feeds sheets when sheet width size information input by the user through an operation panel and the sheet width size detected by the detecting portion match.
In addition, the side regulating plates not only align the sheet widths, but also guide sheets such that jamming of the sheets does not occur due to skew feeding of the sheets when the sheets are fed.
Further, there are cases where a conventional sheet feeding apparatus is commonly used in an image forming apparatus of a different specification.
Incidentally, the conventional sheet feeding apparatus determines whether sheet width size information input to the operation panel and the sheet width size detected by the detecting portion match only when sheet width size information is input to the operation panel.
Therefore, the conventional sheet feeding apparatus has the following issues.
(1) When sheets are fed, jamming of the sheets occurs in the apparatus body of the image forming apparatus, and, while the user is removing the jammed sheets, the user contacts and displaces the side regulating plates in a direction away from the sheets. Further, it is assumed that, after the size is set in the operation panel, the side regulating plates are moved due to a user's unintentional operation. When the user restarts the image forming apparatus without knowing that the positions of the side regulating plates are displaced, the sheet feeding apparatus feeds sheets the widths of which are not regulated by the side regulating plates. As a result, there is a concern that skew fed sheets are jammed in the sheet feeding apparatus or in the image forming apparatus.
Further, when sheets on the manual feed tray run out, the user places sheets having narrower widths than the sheets which have been placed on the manual feed tray so far, and starts the sheet feeding apparatus without changing sheet width size information in the operation panel. Also, in this case, the sheet feeding apparatus skew feeds the sheets having narrow widths which are not regulated by the side regulating plates, and therefore there is a concern that the sheets having narrow widths are jammed in the sheet feeding apparatus or in the image forming apparatus.
(2) When a sheet feeding apparatus is commonly used in an image forming apparatus of a different specification, there are cases where the sheet feeding apparatus feeds sheets which are out of the range of sheet widths which allow the image forming portion of the image forming apparatus to form images.
Assume, for example, that, in a sheet feeding apparatus equipped in an image forming apparatus which forms an image on a sheet up to 210 mm wide (A4-R feed), the user sets the width size to the A4-R width (210 mm) on the operation panel and sets the side regulating plates to the A4-R width. Further, when the sheet feeding apparatus are feeding sheets, jamming of sheets occurs and the user displaces the side regulating plates from the positions for the A4 width (297 mm) while removing the jammed sheets. In this state, if the user erroneously places sheets of the A4 width (297 mm) on the manual feed tray, the sheet feeding apparatus feeds the sheets of the A4 width (297 mm). However, the image forming apparatus cannot form images on the sheets having the width size of 297 mm. Therefore, there are cases where the sheets of the A4 width (297 mm) are jammed in the image forming apparatus. Further, there is a concern that the jammed sheets damage the image forming apparatus.
The present invention provides a sheet feeding apparatus which, when no sheet is temporarily fed and the user displaces the positions of aligning members, can detect that the positions of the aligning members are displaced and stop feeding sheets.